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UNITED STATES PATENTA Ormea.

SAMUEL NOWLAN, OF NEW YORK, N. Y.

IMPROVEMENT IN SAFETY-VALVES FOR STEAM-GENERATORS.

Specification forming part of Letters Patent No. 55,610, dated December19, 1865.

To all whom t may concern:

Be it known that I, SAMUEL NOWLAN, of New York, in the county and Stateof New York, have invented certain new and useful Improvements inSafety-Valves for Steam- Generators; and I hereby declare that thefollowing is a full, clear, and exact description of the same, referencebeing had to the accompanying drawings, in which- Figurel is a sectionalelevation of an apparatus constructed in accordance with this myinvention, and Fig. 2 a horizontal section on line w y in Fig. l.

It is unnecessary here to refer to the shortcomings or defects attendingthe ordinary safety-Valves on steamboilers or other steamgenerators. Thenumerous accidents which almost daily occur in consequence of theuureliable character or sluggishuess of action of safety-valves asheretofore constructed fully illustrates and demonstrates their defects.Moreover, the weighted lever-valve can only be used with advantage onstationary engines, unless combined with guiding devices, while thespring-valves partake of the same difficulties and imperfections of theordinary weighted valves. The fact is, both are defective in this, thatthe pressure of steam must overcome the inertia or adhesion of thevalve, in order to lift it od its seat and to allow steam to escape fromthe boiler. This is the cause of most explosions.

The object, therefore, of this invention is to render the apparatus moresensitive to the variations of pressure of steam and to facilitate itsaction, and thus attain greater safety.

- To enable others to make and use my invention, I shall now proceed todescribe the manner in which the same is or may be carried into effect.

Referring to the drawings, A is the socket by which the apparatus issecured to the boiler. The apparatus consists of a column, C, of alength and diameter proportionate to the capacity of the generator uponwhich it is used. Within this column a concave-convex or otherwiseshaped partition, G, is formed, which is centrally perforated for theadmission of steam through it and out of the column. This partitionforms the seat of a valve-piston, V, which is truly guided by theannular flanges B B', against which the piston has a steam-tight tting.

The piston is provided with four radiating channels, a, terminating intoa central opening, b, which forms a continuation of the hollowpiston-rod D, so that any steam which may surround the piston at thecircumferential openin gs of the side channels, a, will necessarilyescape through the center of the piston and the piston-rod at the upperpart of the column.

The lower part of the piston is provided with an india-rubber disk, c,which is secured onto the piston by a central screw, s. By this means aperfect tight lit is made to the piston in its valve -seat G. There arealso in the lower part of the piston four recesses or channels,f, whichallow steam to escape into the space between the annular anges B B'whenever the piston is raised sufficiently high to establishcommunication through the channels f between the steam-generator and thesaid space.

A ring, R, is secured in the upper part of the column, through which thepiston-rod is capable of an up-and-down play. Against this ring abutsthe upper end of a spiral spring, K, which, winding around thepiston-rod, causes the piston to bear down with'a pressure which is thecalculated pressure of safety less the amount of friction which thepiston has against the annular flanges B B'.

From the foregoing the operation of my improved safety-valve will beunderstood to be as follows Steam acting on the4 under side of thepiston and the spring acting on the opposite side will cause it to playup and down, according to variations of pressure in the boiler. Thepiston, therefore, is never necessarily at rest; consequently there isno inertia or adhesion to be overcome by the sudden formation of a largeamount of steam or by the sudden increase of pressure. When the pressureis such as to lift the piston to a point where the channels fclear theannular ange B', then the steam will rush out into the recess formed bythe iianges B and B', and from the reissue through the ways a, into thecentral opening, l), and out through the hollow piston D. When theinternal pressure in the boiler is thus rclieved, so as to allow thespring K to equilibrate the pressure the piston will descend again inits place, and thus cut off the steam. With this safety-valve may becombined a thermometer, indicating the temperature of 2. Thecombination, with the movable valvepiston provided with steam-channels,as described7 of the hollow piston-rod and helicalspring, when arrangedfor operation as herein set forth.

In testimony whereof I have signed my name to this speoiiication beforetwo subscribing witnesses.

SAMUEL NOWLAN.

Witnesses:

JOHN S. HoLLINGsHEAD, JNO. C. DoUNs.

